This invention relates to an optical connector for use in connecting an optical fiber and a method of processing an end face of the optical fiber.
In recent years, various kinds of optical connectors have been proposed and developed. In one of existing optical connectors, an optical fiber 1 is connected by the use of a cylindrical optical component 2 called a ferrule, as illustrated in FIG. 1. The ferrule 2 has an axial one end bonded and fixed to an end face of the optical fiber 1 and the other end polished into a convex surface 3.
In order to connect two optical fibers to each other, a split sleeve 4 is used as illustrated in FIG. 2. Specifically, the convex surfaces 3 of the ferrules 2 respectively fixed to the optical fibers are butted to each other within the split sleeve 4. By the use of elastic springs (not shown), pressing force is applied to the ferrules 2 as depicted by white arrows in the figure. As a consequence, core portions of the optical fiber 1, which are positioned at the tops of the convex surfaces 3 and serve as optical waveguide portions, are elastically deformed and brought into tight contact with each other. By the above-mentioned connection, it is possible to prevent an air layer being formed between the core portions. Therefore, low-loss connection can be achieved. Such connection in which connection objects are brought into tight contact with each other under the pressing force is generally called PC (Physical Contact) connection.
Recently, following the demand for a smaller size of the optical connector and a narrower pitch, consideration is made of an optical connector for directly connecting the optical fibers without using the ferrules. In the optical connector of the type also, the PC connection is required in order to achieve low loss. The pressing force required for the PC connection is obtained by flexing or bending the optical fibers and utilizing restoring force (hereinafter called a buckling load) produced by bending.
In the optical connector for directly connecting the optical fibers, it is necessary to process the end faces of the optical fibers into mirror surfaces, i.e., to carry out mirror finishing. The mirror finishing may effectively be carried out by cleavage cutting in which a cut face has a mirror surface. By the cleavage cutting, however, the cut face of the optical fiber may have a face angle θ, as illustrated in FIG. 3. It is noted here that the above-mentioned buckling load is on the order between 0.2 and 0.4N. Depending upon the face angle θ, elastic deformation of the optical fibers 5 may be insufficient and sufficiently tight contact can not be assured between the end faces, as illustrated in FIG. 4. In this event, reliable connection can not be achieved. This results in failure in achieving stable optical characteristics and low loss.
Use is also made of a method of fixing the optical fiber to the optical component such as the ferrule by the use of a UV-setting adhesive or a wax and polishing the end face of the optical fiber. However, this method is time-consuming and troublesome because a step of curing the UV-setting adhesive or the wax and a step of removing such fixing agent are required. If the UV-setting adhesive or the wax can not completely be removed but is partially left and adhered to the end face of the optical fiber, optical characteristics will considerably be deteriorated. This results in lack of reliability.